Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013		Dec. 31, 2013
Operating Statistics [Line Items]
US GAAP Based, Net interest income	$ 673	[1]	$ 518	[1]	$ 1,192	[1]	$ 1,023	[1]
US GAAP Based, Other operating income	261		566		761		1,158
US GAAP Based, Total operating income	934		1,084		1,953		2,181
Provision (credit) for credit losses	85		67		101	[2]	88	[2]
US GAAP Based, Operating income, net	849		1,017		1,852		2,093
US GAAP Based, Operating expenses	876	[3]	766	[3]	1,626	[3]	1,534	[3]
Income (loss) before income tax	(27)		251		226		559
Total assets	182,218	[4]	189,524		182,218	[4]	189,524		185,487	[4]
US GAAP Based, Total loans, net	71,574		66,100		71,574		66,100		67,089
US GAAP Based, Goodwill	1,612		2,228		1,612		2,228		1,612
US GAAP Based, Total deposits	115,521		111,735		115,521		111,735		112,608
Adjustments Or Reconciling Items [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(4)	[1]	(3)	[1]	(9)	[1]	(7)	[1]
IFRS Based, Other operating income	4		3		9		7
IFRS Based, Total operating income	0		0		0		0
IFRS Loan Impairment charges	0		0		0	[2]	0	[2]
IFRS Based, Operating income, net	0		0		0		0
IFRS Based Operating expenses	0	[3]	0	[3]	0	[3]	0	[3]
IFRS Based, Profit before income tax expense	0		0		0		0
Total Assets	0		0		0		0
IFRS Based, Total loans, net	0		0		0		0
IFRS Based, Goodwill	0		0		0		0
IFRS Based, Total deposits	0		0		0		0
Aggregate [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	653	[1]	535	[1]	1,166	[1]	1,056	[1]
IFRS Based, Other operating income	310		555		840		1,124
IFRS Based, Total operating income	963		1,090		2,006		2,180
IFRS Loan Impairment charges	144		28		163	[2]	78	[2]
IFRS Based, Operating income, net	819		1,062		1,843		2,102
IFRS Based Operating expenses	800	[3]	810	[3]	1,556	[3]	1,574	[3]
IFRS Based, Profit before income tax expense	19		252		287		528
Total Assets	230,024		246,678		230,024		246,678
IFRS Based, Total loans, net	67,580		62,050		67,580		62,050
IFRS Based, Goodwill	1,264		1,744		1,264		1,744
IFRS Based, Total deposits	95,030		100,913		95,030		100,913
Ifrs Adjustments [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	(16)	[1],[5]	(21)	[1],[5]	(31)	[1],[5]	(38)	[1],[5]
IFRS Based, Other operating income	(6)	[5]	12	[5]	(10)	[5]	38	[5]
IFRS Based, Total operating income	(22)	[5]	(9)	[5]	(41)	[5]	0	[5]
IFRS Loan Impairment charges	(52)	[5]	19	[5]	(48)	[2],[5]	(4)	[2],[5]
IFRS Based, Operating income, net	30	[5]	(28)	[5]	7	[5]	4	[5]
IFRS Based Operating expenses	76	[3],[5]	(27)	[3],[5]	68	[3],[5]	(27)	[3],[5]
IFRS Based, Profit before income tax expense	(46)	[5]	(1)	[5]	(61)	[5]	31	[5]
Total Assets	(47,570)	[5]	(57,199)	[5]	(47,570)	[5]	(57,199)	[5]
IFRS Based, Total loans, net	1,693	[5]	3,144	[5]	1,693	[5]	3,144	[5]
IFRS Based, Goodwill	348	[5]	484	[5]	348	[5]	484	[5]
IFRS Based, Total deposits	(3,128)	[5]	(5,047)	[5]	(3,128)	[5]	(5,047)	[5]
Ifrs Reclassifications [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	36	[1],[6]	4	[1],[6]	57	[1],[6]	5	[1],[6]
IFRS Based, Other operating income	(43)	[6]	(1)	[6]	(69)	[6]	(4)	[6]
IFRS Based, Total operating income	(7)	[6]	3	[6]	(12)	[6]	1	[6]
IFRS Loan Impairment charges	(7)	[6]	20	[6]	(14)	[2],[6]	14	[2],[6]
IFRS Based, Operating income, net	0	[6]	(17)	[6]	2	[6]	(13)	[6]
IFRS Based Operating expenses	0	[3],[6]	(17)	[3],[6]	2	[3],[6]	(13)	[3],[6]
IFRS Based, Profit before income tax expense	0	[6]	0	[6]	0	[6]	0	[6]
Total Assets	(236)	[6]	45	[6]	(236)	[6]	45	[6]
IFRS Based, Total loans, net	2,301	[6]	906	[6]	2,301	[6]	906	[6]
IFRS Based, Goodwill	0	[6]	0	[6]	0	[6]	0	[6]
IFRS Based, Total deposits	23,619	[6]	15,869	[6]	23,619	[6]	15,869	[6]
RBWM [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	212	[1]	206	[1]	410	[1]	421	[1]
IFRS Based, Other operating income	104		82		217		189
IFRS Based, Total operating income	316		288		627		610
IFRS Loan Impairment charges	21		21		23	[2]	53	[2]
IFRS Based, Operating income, net	295		267		604		557
IFRS Based Operating expenses	298	[3]	300	[3]	577	[3]	591	[3]
IFRS Based, Profit before income tax expense	(3)		(33)		27		(34)
Total Assets	19,169		19,563		19,169		19,563
IFRS Based, Total loans, net	16,315		16,508		16,315		16,508
IFRS Based, Goodwill	581		581		581		581
IFRS Based, Total deposits	29,138		31,855		29,138		31,855
CMB [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	202	[1]	172	[1]	389	[1]	342	[1]
IFRS Based, Other operating income	64		77		132		142
IFRS Based, Total operating income	266		249		521		484
IFRS Loan Impairment charges	83		1		90	[2]	15	[2]
IFRS Based, Operating income, net	183		248		431		469
IFRS Based Operating expenses	174	[3]	171	[3]	332	[3]	333	[3]
IFRS Based, Profit before income tax expense	9		77		99		136
Total Assets	26,467		20,799		26,467		20,799
IFRS Based, Total loans, net	25,239		19,693		25,239		19,693
IFRS Based, Goodwill	358		358		358		358
IFRS Based, Total deposits	22,135		21,382		22,135		21,382
GBM [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	109	[1]	125	[1]	206	[1]	234	[1]
IFRS Based, Other operating income	151		295		445		677
IFRS Based, Total operating income	260		420		651		911
IFRS Loan Impairment charges	40		6		55	[2]	9	[2]
IFRS Based, Operating income, net	220		414		596		902
IFRS Based Operating expenses	239	[3]	250	[3]	478	[3]	480	[3]
IFRS Based, Profit before income tax expense	(19)		164		118		422
Total Assets	175,330		197,729		175,330		197,729
IFRS Based, Total loans, net	19,957		19,975		19,957		19,975
IFRS Based, Goodwill	0		480		0		480
IFRS Based, Total deposits	31,935		35,524		31,935		35,524
PB [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	56	[1]	49	[1]	105	[1]	94	[1]
IFRS Based, Other operating income	25		30		50		58
IFRS Based, Total operating income	81		79		155		152
IFRS Loan Impairment charges	0		0		(5)	[2]	1	[2]
IFRS Based, Operating income, net	81		79		160		151
IFRS Based Operating expenses	61	[3]	67	[3]	116	[3]	127	[3]
IFRS Based, Profit before income tax expense	20		12		44		24
Total Assets	8,232		7,499		8,232		7,499
IFRS Based, Total loans, net	6,069		5,874		6,069		5,874
IFRS Based, Goodwill	325		325		325		325
IFRS Based, Total deposits	11,822		12,152		11,822		12,152
Other [Member]
Operating Statistics [Line Items]
IFRS Based, Net Interest Income	78	[1]	(14)	[1]	65	[1]	(28)	[1]
IFRS Based, Other operating income	(38)		68		(13)		51
IFRS Based, Total operating income	40		54		52		23
IFRS Loan Impairment charges	0		0		0	[2]	0	[2]
IFRS Based, Operating income, net	40		54		52		23
IFRS Based Operating expenses	28	[3]	22	[3]	53	[3]	43	[3]
IFRS Based, Profit before income tax expense	12		32		(1)		(20)
Total Assets	826		1,088		826		1,088
IFRS Based, Total loans, net	0		0		0		0
IFRS Based, Goodwill	0		0		0		0
IFRS Based, Total deposits	$ 0		$ 0		$ 0		$ 0

[1] Net interest income of each segment represents the difference between actual interest earned on assets and interest paid on liabilities of the segment adjusted for a funding charge or credit. Segments are charged a cost to fund assets (e.g. customer loans) and receive a funding credit for funds provided (e.g. customer deposits) based on equivalent market rates. The objective of these charges/credits is to transfer interest rate risk from the segments to one centralized unit in Treasury and more appropriately reflect the profitability of segments.

[2] The provision assigned to the segments is based on the segments' net charge offs and the change in allowance for credit losses.

[3] Expenses for the segments include fully apportioned corporate overhead expenses.

[4] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") as of June 30, 2014 and December 31, 2013 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 16, "Variable Interest Entities," for additional information. Assets: Interest bearing deposits with banks, $3 million and $5 million, Securities held-to-maturity, $157 million and $200 million Other assets $458 million and $502 million. Total assets $618 million and $707 million respectively. Liabilities: Long-term debt $92 million and $92 million, Interest, taxes and other liabilities $71 million and $93 million. Total liabilities $163 million and $185 million, respectively.

[5] Represents adjustments associated with differences between IFRSs and U.S. GAAP bases of accounting.

[6] resents differences in financial statement presentation between IFRSs and U.S. GAAP.